SAS/GRAPH Software: Reference

About Device Drivers

To produce graphics output on a graphics output device, SAS/GRAPH software uses a device driver. Device drivers are the components of SAS/GRAPH software that translate the device-independent output from SAS/GRAPH procedures into the appropriate commands to produce graphics output on particular output devices. Device drivers contain settings that determine the default appearance of the output, such as dimensions and orientation, cell size, colors, and hardware fonts. They can also contain host commands that are issued before and after the driver produces output.

A device driver is composed of two parts:

a device entry in a SAS catalog
an executable module.

The device entry is a SAS catalog entry of type DEV. It is created and accessed with the GDEVICE procedure and explicitly refers to the executable module. The device entry contains device parameters whose settings can control

the appearance of the output
the destination to which the output is sent (native SAS/GRAPH drivers only)
communications between the operating environment and the device
how the device generates the output.

You can change these settings either by modifying the device parameters using the GDEVICE procedure, or by overriding the parameter settings using graphics options in a GOPTIONS statement. For details, see Controlling Output with Device Drivers.

The executable module is a program that produces the device-specific commands from the device-independent output of a SAS/GRAPH procedure. The executable module uses the parameters specified in the device entry to tell it exactly how to do so.

SAS/GRAPH software provides device entries for your operating environment in the Institute-supplied catalog, SASHELP.DEVICES.

If your site has created custom device entries, they may also be stored in SASHELP.DEVICES, although typically custom devices are stored in the catalog GDEVICE0.DEVICES. For more information about custom device entries, see About Device Catalogs or ask your SAS Support Consultant.

Types of Device Drivers

Most of the device drivers in SASHELP.DEVICES are SAS/GRAPH native device drivers, which are those SAS/GRAPH drivers that produce output in the native language of the device. For example, the PS300 driver is a "native device driver" because it directly produces PostScript output.

Some operating environments also use host drivers, which make generic calls to the print driver that the user has selected in Print Setup. The print driver is what writes out the output in the native language of the device.

How Device Drivers Are Assigned

Because many characteristics of the graphics output depend on parameter values that are stored in the device entry, SAS/GRAPH procedures that produce graphics output must know which device driver to use before they begin processing.

Usually SAS/GRAPH automatically selects a device driver for you and you are not required to explicitly specify one. If you use the GRAPH window to display graphics output, SAS/GRAPH selects a device driver that is appropriate for your device. The default device driver for your site may also be selected by your SAS Installation Representative.

If you submit a SAS procedure without specifying a device driver and your display device does not support the GRAPH windows or you are running outside the SAS Display Manager, SAS/GRAPH prompts you for a driver name.

Whether or not a default device is assigned, you can always explicitly assign a device driver. See Selecting a Device Driver for more information.

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